It must be appreciated that one highly acceptable and widely employed means by which to effect a driving connection between the turbine hub of a torque converter and the output shaft of the torque converter employs a concentric engagement therebetween. In addition, a driving connection between the rotating cover on the impeller, or pump, portion of the torque converter and the transmission pump and/or a power take-off, may be achieved by the engagement of a plurality of axially oriented teeth on a drive hub presented from the impeller portion of the torque converter with an opposed plurality of axially oriented teeth on the drive gear of a transmission pump or power take-off, in what is often designated as a "running fit" therebetween.
The several driving connections heretofore described are generally secured by a single fastening means in the nature of a bolt which is received within an axially oriented threaded bore in the end of the turbine output shaft. To expand upon the explanation of a typical power train which utilizes a torque converter to connect between the engine and the transmission of a vehicle, as well as between the engine and the transmission pump and/or a power take-off, the torque converter is filled with a fluid, such as oil, and the impeller portion of a typical torque converter unit is conventionally connected to the crankshaft of a power source, such as an engine, by way of a flex-plate that is secured to the impeller cover.
A typical torque converter contains not only the impeller and a turbine, but also a stator or reactor assembly and a combined pressure plate and damper assembly which, when applied, provides a direct mechanical coupling of the engine to the turbine output shaft. The direct driving connection effected by the combined pressure plate and damper assembly couples the engine directly to the transmission by a series of controls which are not germane to the present invention and they will not, therefore, be further described. Rather, the present invention is directed to the structural arrangement of the fastening connection between the turbine hub and the turbine output shaft as affected by the driving connections between those two components as well as between the impeller cover and the transmission pump and/or a power take-off.
In a typical installation, the turbine hub is received concentrically about the turbine output shaft so that a plurality of radially inwardly directed splines on the interior of the turbine hub interact with a complimentary plurality of radially outwardly directed splines on the turbine output shaft to accomplish the driving connection therebetween. As such, rotation of the turbine hub will simultaneously effect rotation of the turbine output shaft. In addition, a plurality of axially oriented teeth on a drive hub presented from the rotating impeller cover engage an opposed plurality of teeth on the transmission pump and/or the power take-off, to effect a driving connection therebetween so that rotation of the impeller cover will effect operative rotation of the transmission pump and/or the power take-off.
The aforesaid driving connection between the turbine hub and the turbine output shaft as well as the driving connection between the drive hub on the impeller cover and the transmission pump and/or the power take-off, are typically secured by the aforesaid fastening means, such as a bolt, which is tightened into the axially oriented bore in the end of the turbine output shaft. The fastening means operatively engages the turbine hub, as through a thrust washer interposed therebetween, axially to secure the torque converter in position on the output shaft, and the fastening means, if a bolt, is generally torqued to a force moment of prescribed value.
Unfortunately, the driving connection between the turbine hub and the output shaft, as well as the driving connection between the drive hub presented from the impeller cover and the transmission pump and/or the power take-off, cannot be visually observed during assembly. Thus, should any one or more of these connections be misaligned or improperly seated, that fact might well go unnoticed, and so long as the fastening means can be secured within the axially oriented receiving bore in the output shaft, it can be tightened, and the improper seating or misalignment, will continue to go unnoticed. When the fastening means is secured to the proper tightness, as determined by meeting the specifications for the proper force moment, damage can result to the torque converter unit, the transmission pump and/or the transmission unit as a result of an excessively large axial load having been applied to whichever of the driving connections are misaligned inasmuch as the fastening means, by virtue of having been torqued to the prescribed force moment, is applying an improper axial load to the misaligned, or improperly seated, driving connection(s). However, the misalignment is generally found during final assembly and test with an engine. Obviously, this results in additional expense required for teardown and reassembly.